SB-520-2
29
6.4
Evacuation
Switch on oil heater in the oil separator.
Open the shut-off valves. Keep the shut-off valve in the
oil injection line closed. Use a vacuum pump to evacu-
ate the entire system, including the compressor, on the
low and the high pressure sides. With the vacuum
pump shut off, a "standing vacuum" lower than
1.5 mbar must be achieved. Repeat the operation sev-
eral times if necessary. After the evacuation, open the
shut-off valve in the oil injection line.
6.5
Charging with refrigerant
DANGER
Risk of bursting of components and pipes due to
liquid excess pressure while charging liquid re-
frigerant.
Serious injuries are possible.
Avoid overcharging the system with refrigerant
under all circumstances!
!
!
NOTICE
Risk of wet operation by charging liquid refriger-
ant!
Measure out extremely precise quantities!
Maintain the discharge gas temperature well
above the condensing temperature:
with NH
3
at least 30 K.
!
!
NOTICE
Lack of refrigerant causes low suction pressure
and superheat condition!
Observe the application limits.
• Before charging with refrigerant:
– Use approved refrigerants only (see chapter Ap-
– Switch on the oil heater.
– Check the oil level in the oil separator.
– Do not switch on the compressor!
• Charge condenser or receiver, on systems with
flooded evaporator, also the evaporator or liquid sep-
arator directly with liquid refrigerant.
• After commissioning, it may be necessary to add re-
frigerant: While the compressor is running, charge
with refrigerant on the suction side, preferably at the
evaporator inlet or in the liquid separator.
6.6
Tests prior to compressor start
• Oil level in the oil separator (in the sight glass
range).
• Oil temperature in the oil separator (approx. 15 ..
20 K above ambient temperature).
• Setting and function of the safety and protection
devices.
• Setpoints of the time relays.
• Cut-out pressures of the high-pressure and low-pres-
sure cut-outs.
• Cut-out pressures of the pressure switches. Record
the setting.
• Check if the shut-off valves in the oil injection line
are open.
!
!
NOTICE
Do not start the compressor if it was flooded
with oil due to faulty operation! It is absolutely
necessary to empty it!
Internal components may be damaged.
Close shut-off valves, depressurize the com-
pressor and drain oil via drain plug on the com-
pressor.
6.7
Compressor start
6.7.1
Checking the rotation direction
!
!
NOTICE
Risk of compressor failure!
Operate the compressor only in the intended ro-
tation direction!
Check the rotation direction during the first compressor
start:
• Connect the pressure gauge to the suction shut-off
valve. Close the valve spindle and open again by
one turn.
• Let the compressor start for a short time (approx.
0.5 .. 1 s).
• Correct rotation direction: Suction pressure drops im-
mediately.
• Incorrect rotation direction: Suction pressure in-
creases.
Reverse the polarity of the terminals on the common
feed line.
